A medical imaging installation in the form of an x-ray computed tomography installation is disclosed, for example, in U.S. Pat. No. 4,117,337. Two lasers are used to project in each case a cruciform light pattern onto the body surface of a patient in order, for example, to display the position of a scanning plane of the x-ray computed tomography installation.
In the field of medicine, the treatment of a patient, for example, frequently also requires a specific position to be marked on the patient's body surface. Such a procedure is performed, for example, when preparing for surgery on the patient, recorded images of the patient being used in order to define the specific position. Thus, it is currently customary, for example when using an x-ray computed tomography installation, to undertake a so-called planning scan of the patient in which images of the patient are obtained in sequence mode or spiral mode in order to secure an impression of the topographic conditions and to define the surgery position and, if appropriate, the surgery axis for the operation. Upon conclusion of the planning, the surgery position defined with the aid of the images, which can, for example, be a puncture site for a biopsy needle, is sought out on the patient and, if appropriate, the puncture angle for the surgery is defined.
In order to find the puncture site on the patient's body surface, when use has been made of an x-ray computed tomography installation in recording the images of the patient, the latter, who is supported on the support apparatus of the computed tomography installation, is adjusted together with the support apparatus in such a way that the slice position selected during planning is approached and marked with the aid of a so-called laser light sight that is arranged on the computed tomography installation. In what follows, an x-ray positive marking is applied at the site on the patient's body surface at which the correct position of the puncture site is thought to be from the planning. Finally, a control scan is used to check whether the site has been correctly marked. If the site has been missed, the marking must be corrected, and a further control scan is required.
There can be a need in some cases for a number of control scans in order to find the correct puncture site on the patient's body surface. In unfavorable cases, the patient is thus exposed repeatedly to x-radiation solely in order to find the surgery position, and this is undesirable. Moreover, this procedure can make commands on a relatively long time for preparing the surgery, and this has a negative effect on the workflow in the medical facilities. Otherwise, the surgery itself is generally performed under x-ray control, that is to say during surgery images of the patient are obtained at specific points in time in order to be able to observe the progress of the surgery.